Abstract
The increasing demand for oil and gas before the global recession was driving up prices and the focus of oil and gas producers was to maintain and maximise production from every available facility. Older unreliable facilities were being rapidly upgraded including the replacement of Safety Instrumented Systems (SIS) such as emergency shutdown (ESD) systems, process shutdown (PSD) systems, Emergency Depressurisation (EDP) systems and fire and gas (F&G) systems.
Traditionally, the replacement of such safety critical systems is undertaken during a plant shutdown opportunity to ensure that process integrity is maintained and to facilitate comprehensive commissioning and validation without the presence of the process hazards. However, in the era of high oil and gas demand we saw more and more SIS replacement projects being undertaken whilst the process was still fully operational, even though this potentially compromised the integrity of a facility.
Oil and gas are finite resources and high prices will inevitably return. This paper summarises the findings of a number of IEC 61508 and IEC 61511 compliance audits undertaken for SIS replacement projects on live production facilities.